1. Field of the Invention
The present invention relates to a two-way electromagnetic valve and, more particularly, to a two-way electromagnetic valve which has a ball displaced by the drive of electromagnetic means in response to an electric signal to permit or cut-off flow therethrough.
2. Description of the Prior Art
The prior art is exemplified in FIGS. 8 and 9. A normally-closed two-way electromagnetic valve is constructed, as shown in FIG. 8, of a casing 1, a core 2, an electromagnetic coil 4 wound on a bobbin 3, a terminal 5 mounted in resin molding 9, a yoke 6, a coil spring 7 and a plunger 8. The normally-closed type two-way electromagnetic valve has, in its valve portion, a base 10, formed with an input port 12 and a discharge port 13, and a ball 11 adapted to seat in the valve seat of base 10 by the forward movement of the plunger 8.
On the other hand, as shown in FIG. 9, a normally-open two-way electromagnetic valve is constructed of a casing 21, an electromagnetic coil 24 wound on a bobbin 23, a terminal 25 set in a resin molding, a yoke 22 and a plunger 27. The normally-open two-way electromagnetic valve has its valve portion including a slender base 30 formed with an input port 32 extending deeply into the electromagnet portion and a ball adapted to seat in the valve seat of the base 30 by the forward movement of the plunger 27. Moreover, the casing 21 is formed with a discharge port 33 opposite input port 32.
Comparing FIGS. 8 and 9 it can be seen that in the prior art the normally-closed type two-way electromagnetic valve and the normally-open type two-way electromagnetic valve are constructed so differently that they are assembled of almost entirely different parts.
In other words, since parts are not shared between the valves of the two types, there arise problems in that the production cost is high and many parts have to be managed.